FDOUT
bus_space_write_1(iot, ioh, FDOUT, drive | FDO_FRST | FDO_MOEN(drive));
bus_space_write_1(iot, ioh, FDOUT, FDO_FRST);
bus_space_write_1(fdc->sc_iot, fdc->sc_ioh, FDOUT, status);
bus_space_write_1(iot, ioh, FDOUT, 0);
bus_space_write_1(iot, ioh, FDOUT, FDO_FRST);